The present invention relates to a process for reducing the content of cholesterol and of free fatty acids in an animal fat and to the fat material so obtained.
Animal fats, like milk fat (butter, cream . . . ), suet and lard contain sterols and, in particular, cholesterol as well as free fatty acids.
In spite of its vital role, cholesterol is considered as being an element of risk for cardiovascular diseases, and the development of atherosclerosis in man has often been associated closely with the content of cholesterol in the blood.
Attempts have consequently been made to reduce the amount of cholesterol present in animal fats used in human food.
Cholesterol can be extracted by evaporation under high vacuum at a temperature of 240 to 280 degrees Celsius. This treatment results however in the loss of natural aromatic volatile elements which also evaporate.
The percolation of the fat at a temperature of 70 to 90 degrees Celsius over activated charcoal also enables reduction in the content of cholesterol but the activated charcoal also fixes other natural substances of the fat like especially aromatic components, antioxidants and color.
The extraction of cholesterol with carbon dioxide in supercritical conditions, that is to say at pressures above 100 bars, is a technique difficult to use industrially. Moreover the extraction of the cholesterol is not selective. For example, in the treatment of fat from milk, a considerable part of short chain triglycerides will also be extracted.
Patent application EP-A-0 256 911 describes a process for removing cholesterol from fats of animal origin, according to which the fluidized fat is contacted with a cyclodextrin; this contact is prolonged with stirring under a non-oxidizing atmosphere and at a temperature comprised between the melting point of the fat and 80 degrees Celsius for a period of 30 minutes to 10 hours, in the course of which complexes between the cholesterol and cyclodextrin would be formed, after which water is added and said complexes are extracted from the fat by entrainment into the aqueous phase so formed which is then separated from the fatty phase.
This process is not only relatively long but it only permits a limited reduction of the cholesterol content in a single operation. A single operation only permits in fact the removal of 18 to 33% of the initial cholesterol. To obtain a greater extraction, several successive operations must thus be carried out, if necessary, followed each time by a step of washing the lipid phase. With three successive extractions 41% of the initial cholesterol can be extracted. In theory, it would be possible in this way to remove up to 80% of the initial cholesterol. Furthermore no mention is made in EP-A-0 256 911 of any removal whatever of free fatty acids.
It is a object of the present invention to overcome the aforementioned drawbacks and to provide a process still based on extraction of cholesterol from animal fats by cyclodextrin, but arranged so that it enables, rapidly and efficiently, in a single operation, a considerable reduction of the content of cholesterol and at the same time an appreciable reduction of the content of free fatty acids in a fat of animal origin, to be achieved.
By fat of animal origin is meant particularly butter, dairy cream, anhydrous dairy fat, suet and lard.